This article is a history of liquidity presented as interaction between metaphors and theoretical concepts in social contexts. While taking note of Zygmunt Bauman’s metaphor “liquid modernity,” the study instead surveys the wider conceptual field. The text turns around mercantile liquidity (liquidity as clarification) and liquidity in modern economics (characteristic of all assets), as well as older metaphors, notably the famous phrase of the Communist Manifesto, “all that is solid melts into air” (Alles Ständische und Stehende verdampft), which is revealed to have resonance in texts by poets, notably Heinrich Heine. The main result is the historical consistency of the field, where liquidity is a promise of knowledge and clarity.